Diving Indonesia Periplus Adventure Guid. David Pickell
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a variety of forms, ranging from branching thickets to table-like formations. The tables are considered to be a defense mechanism, as the Acropora quickly grows outward, shading any other corals that might try to overgrow it.
Another branching coral often recognized by divers is the needle coral Seriatopora hystrix, sending up delicate, pointed branches of cream, blue or pink. Seriatopora is usually found in quiet, rather shallow water.
Smaller corals. Some of the smaller coral colonies have distinct, interesting shapes. These corals are not primary reef builders, but colonize already established areas of the reef.
The mushroom corals (family Fungiidae) are common in Indonesia. These form carbonate skeletons that are flat and oval-shaped, perhaps 15-30 centimeters inches long, with fine, radial structures reminiscent of the "gills" of a mushroom. The skeletons are not attached to the reef, and particularly on drop-off reefs, are often knocked upside down by currents. These corals are capable of limited movement, and can usually right themselves eventually. The long-tentacled Heliofungia actiniformis is often mistaken for a sea anemone.
The flower corals (Euphyllia) are not as common as Fungia, but can be quite beautiful. They form a maze of flat plates that stick up vertically 10-20 centimeters and cover an area 50 centimeters or even much more in diameter. These corals have long, colorful tentacles, which they extend during the day. Euphyllia tolerates turbid water, and can be found growing on patch reefs in back reef channels.
The very bright orange polyps of the coral Tubastrea (or the similar Dendrophyllia) can be seen in small clusters, usually in low-light areas such as deep on the reef or under overhangs. These finger-sized polyps can easily be mistaken for anemones. They are true scleractinian corals, however, and secrete a very fragile internal skeleton. Tubastrea contains no zooxanthellae and receives all its nutrition by capturing plankton. At night, you can watch the polyps feeding by using your light to attract the plankton within reach of the polyps' tentacles. (If your light is very bright, shade it so the polyps won't retract.)
Anemones
Despite their soft and fleshy appearance, sea anemones (order Actinaria) are more closely related to stony corals than soft corals. The giant anemones commonly encountered in Indonesia contain symbiotic algae and are most abundant in relatively shallow areas. They can be seen growing in sand, or tucked into the coral rock in the shallows or at the lip of drop-off reefs.
Like the corals, color and even shape varies widely in the giant anemones, and they are often very difficult to identify. In Indonesia, one can find the long-tentacled Heteractis, the short-tentacled carpet anemone, Stichodactyla, and the unusual Entacmaea quadricolor, with bulbous-tipped tentacles. These anemones are large, sometimes growing to half a meter or more in diameter, although what at first seems to be one anemone is sometimes a group of several.
Discovering New Species
For the diving scientist, Indonesian waters are the most exciting in the world. Not only can "new" species be found on just about every dive, but so much of the behavior of these animals is still unknown that underwater observations are full of surprises.
Scuba has radically changed the way scientists study marine animals. No longer is it necessary to collect everything to study in an aquarium, an artificial environment that often produces artificial behavior, or to collect species the old way—netting, trapping, or even poison. A diver can collect very selectively, and make observations without interfering with the animals' ways of life.
Innumerable small crustaceans and other benthic creatures living in the cracks and crevices of Indonesian reefs go undescribed by science. Even among the best-known reef animals—the fishes—new discoveries are made regularly.
The Grandfather of Ichthyology
To find new species of fish, a good eye and thorough knowledge of the literature serves one better than an academic degree. The grandfather of Indonesian ichthyology was Pieter Bleeker, a Dutch army doctor with a keen interest in fishes. He arrived in Jakarta in 1842, and over the following 30 years produced some 500 papers that became the foundation of his famous, nine-volume Atlas Ichthyologique (1862-78).
Unlike many 19th century scientists, who were for the most part simple taxonomists, Bleeker had a very modern understanding of the inter-relationship of species. His work is highly respected by today's scientists.
Finding New Species
Bleeker's work was so good that species described 100 years ago are still waiting to be "re-discovered." It is amazing how many deep-water fishes were collected in those days and never seen again. But scientists tend to concentrate on these, and the intertidal areas are often overlooked. A knowledgeable diver, with sharp powers of observation, has a very good chance of finding an unknown animal on just about any dive in Indonesia.
The red-headed wrasse, Halichoeres rubricephalus, is sexually dichromic (male at top). This beautiful wrasse was discovered by Kuiter in 1986 in Maumere Bay. Common there, it has not been seen anywhere else.
I have been visiting the Flores Sao Resort on a regular basis since 1986, photographing and observing the animal life of Maumere Bay. Despite my many dives in these waters, new species turn up on every trip. Often a "new" species looks very similar to a well-known one, and thus has been overlooked. But in other cases the new species is so spectacular one wonders how it could possibly have ever gone unnoticed.
I started underwater photography 20 years ago, and even among my first dives with a camera, I photographed things that I have never seen since. I always take the picture first, and try to sort out the story later. The underwater world is so diverse you may never see it again.
— Rudie Kuiter
Giant anemones are easy to spot because they nearly always host a pair, or small group of clownfish (Amphiprion and Premnas). (See "Clownfishes and their Sea Anemone Hosts," page
46.) These fish are not the only animals to take advantage of the security of the anemone's stinging tentacles. Porcelain crabs (Neopetrolisthes) and shrimps are also anemone commensals.
Corallimorphs. These animals (order Corallimorpharia) have some of the characteristics of anemones, and others of corals. In fact, however, they look like small anemones. They are mostly colonial, and consist of flat disks, 2-4 inches in diameter, with a smooth, napped or tentacled surface. One genus, Discosonia, is particularly colorful, overgrowing rocks with its bright blue, purple or red disks.
Soft corals and gorgonians
These animals (subclass Alcyonaria) are among the loveliest of the cnidarians. In the clean, plankton-rich waters of Indonesia, soft corals and gorgonians— sea whips or sea fans—are common. Some contain zooxanthellae, but many frequent the deeper parts of the reef, where they filter plankton from the water. Semi-precious pink "coral" is a gorgonian (Corallium), harvested from deep waters off Japan and in the Mediterranean.
Soft corals. Soft corals, as the name suggests, lack the hard limestone skeletons of their reef-building relatives. Instead, the numerous polyps that make up the colony are supported by a fleshy central "body"; in some cases strengthened by spicules, spines of silica or calcium.
Soft corals (order Alcyonacea) have few obvious defense mechanisms, and might seem to be vulnerable to attack by predators and parasites, or to fouling by overgrowth. The animals avoid these problems by secreting various bioactive substances, a kind of chemical defense. Substantial efforts are being made by biochemists and pharmaceutical companies to identify compounds in soft corals—and also sponges—that may have properties useful in medicine. Since many of these compounds have evolved to prevent alien growths, they are receiving attention as potential anti-cancer drugs.
A very common group of soft corals in Indonesia are the leather corals (Lobophyturn, Sarcophyton and Sinularia) so-named because of their color and texture. These corals grow as wrinkled lobes in well-lit, shallow areas of reef. Because of their symbiotic zooxanthellae, they are a dull brown, sometimes with a slightly green or yellow tinge. When their white polyps are extended for